Nursing Elites

1. What is the primary function of the CRISPR-Cas9 system in gene editing?

• A. To amplify specific DNA sequences.
• B. To cut DNA at specific locations.
• C. To deliver genes into cells.
• D. To sequence entire genomes.

Correct answer: B

Rationale: The CRISPR-Cas9 system is a powerful tool used in gene editing to precisely target and cut DNA at specific locations within the genome. This system consists of a guide RNA that directs the Cas9 enzyme to the desired DNA sequence, where it creates a double-strand break. This break can then be repaired by the cell's natural DNA repair mechanisms, allowing for the introduction of specific genetic modifications. Options A, C, and D are incorrect as they do not accurately describe the primary function of the CRISPR-Cas9 system in gene editing. Amplifying DNA sequences, delivering genes into cells, and sequencing entire genomes are not the main functions of the CRISPR-Cas9 system, which is primarily focused on precise DNA cutting for targeted genetic modifications.

2. Which type of reaction builds larger and more complex molecules from smaller ones, requiring energy?

• A. Catabolic reaction
• B. Anabolic reaction
• C. Exothermic reaction
• D. Hydrolytic reaction

Correct answer: B

Rationale: The correct answer is 'Anabolic reaction.' Anabolic reactions involve the synthesis of larger and more complex molecules from smaller ones, requiring an input of energy, often in the form of ATP. These reactions are essential for processes like growth, repair, and the building of cellular structures. Catabolic reactions, on the other hand, break down larger molecules into smaller ones, releasing energy. Exothermic reactions release heat, while hydrolytic reactions involve the breakdown of molecules with the addition of water. Therefore, choices A, C, and D are incorrect as they do not describe the process of building larger and more complex molecules from smaller ones with the requirement of energy.

3. How many neutrons and electrons could a negative ion of sulfur have?

• A. 16 neutrons, 16 electrons
• B. 16 neutrons, 17 electrons
• C. 17 neutrons, 16 electrons
• D. 17 neutrons, 17 electrons

Correct answer: B

Rationale: A negative ion of sulfur would have 16 protons and 17 electrons since it gains one electron. The number of neutrons in an ion does not change, so the neutrons would remain at 16. Therefore, the correct answer is 16 neutrons and 17 electrons, which corresponds to choice B. Choice A is incorrect as it does not account for the extra electron gained by the negative ion. Choices C and D are incorrect because they propose a change in the number of neutrons, which is not affected by the ionization process.

4. What is the primary source of energy entering most ecosystems?

• A. Chemical energy stored in bonds
• B. Thermal energy from the Earth's core
• C. Light energy from the sun
• D. Kinetic energy from wind and water

Correct answer: C

Rationale: In most ecosystems, the primary source of energy is sunlight. This energy is captured by plants and other photosynthetic organisms through the process of photosynthesis. These organisms convert light energy into chemical energy stored in the bonds of organic molecules, such as glucose. This stored chemical energy is then passed on to other organisms in the ecosystem through the food chain, making sunlight the fundamental source of energy for most ecosystems. Thermal energy from the Earth's core (option B) is not a primary source of energy for ecosystems, as it is not readily accessible to most organisms. Kinetic energy from wind and water (option D) can play a role in some ecosystems, but it is not the primary source of energy. Chemical energy stored in bonds (option A) is a form of energy that is ultimately derived from the sun through photosynthesis, making it a product of the primary energy source rather than the primary source itself.

5. What is the primary function of the lymphatic system?

• A. To transport oxygen throughout the body
• B. To filter blood and remove waste
• C. To fight infection and remove excess fluid
• D. To transport hormones

Correct answer: C

Rationale: The correct answer is C: 'To fight infection and remove excess fluid.' The lymphatic system plays a crucial role in the body's immune response by fighting infections through lymphocytes and removing excess fluid from tissues, maintaining fluid balance. It does not primarily transport oxygen, filter blood, or transport hormones. While the lymphatic system is involved in lipid absorption and transport, its primary functions are related to immunity and fluid balance.

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